It is conventional practice to apply the cuff of a blood pressure monitoring device to a subject's limb, in particular to his or her upper arm or wrist, and inflate it until arterial occlusion sets in. The fluid pressure system provided for this purpose typically comprises a pump for cuff inflation, a valve for discharge of the pressure fluid, and a pressure sensor for detecting the cuff pressure from whose fluctuations caused by the blood pressure during the inflation and deflation cycles the blood pressure is then determinable by means of an evaluating unit.
For connecting the components of the fluid pressure system it is known to use a rubber tubing having arranged around it all the components exposed to pressure, in which arrangement however both the assembly and the design freedom of the individual components are subject to restrictions. The fluid channels may be formed by tubing or molded parts coupled together internally. An automated assembly of this “internal tubing” is practically not possible because of the soft material properties and the small dimensions of the tubes.
From EP 0 769 266 A1 a blood pressure monitoring device is known in which the fluid channels are integrally formed in a mounting module for the components of the fluid pressure system. In this device, the injection-molded mounting module has on its upper side recesses in the form of grooves which are closed and sealed with a film material adhesive-bonded to the upper side so that fluid channels are produced. For the film to adhere it is however necessary for the upper side to be plane or to have no more than a one-dimensional curvature, which imposes limitations on the freedom of design and relative arrangement of the individual components. In addition, the film is relatively sensitive and hence subject to increased wear. Furthermore, the film is extensible to a considerable degree which may result in a pressure pulse characteristic developing in the fluid channel which produces a measurement error. Finally, contact with the cover film entails the risk of pressure surges occurring in the fluid channel, hence introducing measurement errors. For a fluid-tight configuration of the connection between film and upper side a coating of hot-melt adhesive was used which requires an appropriate temperature treatment.
It is therefore an object of the present invention to provide an improved blood pressure monitoring device of the type initially referred to, an improved method of manufacturing the parts mounting module of the blood pressure monitoring device, and a die for implementing said method, which avoid the known shortcomings of the prior art. The aim is in particular to provide an improved mounting module for the components of the fluid pressure system, which affords ease of assembly of the blood pressure monitoring device and contributes to a compact design of the blood pressure monitoring device.